Spaces defined by Lie group endomorphisms ($\Phi$-spaces)
A. S. Fedenko
Abstract:
À
$\Phi$-space is a triple
$(G,H,\Phi)$ consisting of a connected Lie group
$G$, a closed subgroup
$H$ of
$G$ and an analytic endomorphism
$\Phi$ of
$G$ such that
$H$ lies between
$G^\Phi$ and the identity component of
$G^\Phi$, where
$G^\Phi$ denotes the closed subgroup of
$G$ formed by all the elements left fixed by
$\Phi$. The symmetric space is obtained in the case
$\Phi^2=1$. A local triple is triple
$\mathfrak g,\mathfrak h,\varphi$ consisting of the finite-dimensional real Lie algebra
$\mathfrak g$, a subalgebra
$\mathfrak h$ of
$\mathfrak g$, and an endomorphism
$\varphi$ of
$\mathfrak g$ such that
$\mathfrak h$ consist of all elements of
$\mathfrak g$ left fixed by
$\varphi$. If
$\varphi^2=1$, then
$(\mathfrak g,\mathfrak h,\varphi)$ is a symmetric Lie algebra.
Every
$\Phi$-space
$(G,H,\Phi)$ gives rise to a local triple
$(\mathfrak g,\mathfrak h,\varphi)$ in a natural manner;
$\mathfrak g$ and
$\mathfrak h$ are the Lie algebras of
$G$ and
$H$, respectively, and
$\varphi=d\Phi_e$, where
$e$ is identity element of
$G$. Conversely, if
$(\mathfrak g,\mathfrak h,\varphi)$ is a local triple and if
$G$ is a connected, simply connected Lie group with Lie algebra
$\mathfrak g$, then the endomorphism
$\varphi$ of
$\mathfrak g$ induces an endomorphism
$\Phi$ of
$G$ and, for any subgroup
$H$ lying between
$G^\Phi$ and the identity component of
$G^\Phi$, the triple
$(G,H,\Phi)$ is à
$\Phi$-space. In § 4 all
$\Phi$-spaces are described which generate the local triple
$(\mathfrak g,\mathfrak h,\varphi)$, where
$\mathfrak g$ is the semi-simple compact Lie algebra. In § 5
$\Phi$-space
$(G,Í,\Phi)$ is considered for which
$G$ is the semisimple compact Lie group acting effectively on
$G/H$ and
$\Phi$ is of finite order. It is shown that the identity component of a group of isometries of space
$G/H$ coincides with
$G$. In § 6 a classification of periodic automorphisms of classical compact groups and corresponding
$\Phi$-spaces is given. In § 7 is considered a corresponding classification for classical noncompact groups. This classification is based on the results of § 6 and on a Theorem in [20]. Let
$G$ be a Lie group with a finite number of connected compo nents, and let
$A$ be a finite subgroup of the group of automorphisms of
$G$. Then there exists a maximal ompact subgroup
$K$ of
$G$ which is stable under
$A$.